U.S. patent number 4,657,239 [Application Number 06/633,118] was granted by the patent office on 1987-04-14 for sheet aligning device.
This patent grant is currently assigned to Ricoh Company, Ltd.. Invention is credited to Masumi Ikesue, Yasuhiro Takahashi.
United States Patent |
4,657,239 |
Ikesue , et al. |
April 14, 1987 |
Sheet aligning device
Abstract
A sheet aligning device including a pair of side walls located
parallel to each other and defining therebetween a space for
stacking a plurality of sheets. At least one of the side walls is
movable in reciprocatory movement widthwise of the sheets stacked
between the side walls to force the sheets against the other side
wall so as to align the sheets widthwise thereof which is
perpendicular to the direction in which they are delivered. The
sheet aligning device includes at least one sensor for sensing the
magnitudes of displacements of the sheets widthwise thereof and
producing an output for adjusting at least one of the frequency,
speed and stroke of the reciprocatory movement of the at least one
side wall in accordance with the magnitudes of the
displacements.
Inventors: |
Ikesue; Masumi (Tokyo,
JP), Takahashi; Yasuhiro (Tokyo, JP) |
Assignee: |
Ricoh Company, Ltd. (Tokyo,
JP)
|
Family
ID: |
27316519 |
Appl.
No.: |
06/633,118 |
Filed: |
July 20, 1984 |
Foreign Application Priority Data
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Jul 20, 1983 [JP] |
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58-132546 |
Jul 20, 1983 [JP] |
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58-132547 |
Jul 26, 1983 [JP] |
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58-135151 |
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Current U.S.
Class: |
271/227; 271/240;
271/248; 271/255 |
Current CPC
Class: |
B65H
9/101 (20130101); B65H 31/38 (20130101); B65H
9/106 (20130101) |
Current International
Class: |
B65H
31/38 (20060101); B65H 31/34 (20060101); B65H
9/10 (20060101); B65H 009/06 () |
Field of
Search: |
;271/227,228,238,239,240,248,249,250,253,254,255,221,222,3.1
;414/28 ;198/434,456 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0000302 |
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Jan 1982 |
|
JP |
|
0184042 |
|
Nov 1982 |
|
JP |
|
0195063 |
|
Nov 1982 |
|
JP |
|
2034025 |
|
May 1980 |
|
GB |
|
Primary Examiner: Kashnikow; Andres
Assistant Examiner: Graham; M. C.
Attorney, Agent or Firm: Oblon, Fisher, Spivak, McClelland
& Maier
Claims
What is claimed is:
1. A sheet aligning device comprising a pair of side walls located
on opposite sides of sheets successively delivered at intervals, at
least one of said side walls being movable in reciprocatory
movement to bring the sheets into alignment with each other
widthwise thereof which is perpendicular to the direction in which
the sheets are delivered, wherein the improvement comprises:
detecting means for detecting, before the sheets are aligned
widthwise thereof, a displacement of each of the sheets widthwise
thereof while the sheet remains aligned with a reference line
lengthwise of the sheets and a displacement of each of the sheets
in which the sheet is skewed with respect to the reference line,
said detecting means producing an output for altering at least one
of the frequency, speed and stroke of the reciprocatory movement of
at least one side wall when a sheet aligning operation is
performed.
2. A sheet aligning device as claimed in claim 1 mounted in
association with a tray on which the sheets are stacked, wherein at
least one reciprocating side wall moves across the tray on which
the sheets are stacked.
3. A sheet aligning device as claimed in claim 1 or 2, wherein said
detecting means is located on an upstream side of the tray with
respect to the direction in which the sheets are delivered to the
tray.
4. A sheet aligning device as claimed in claim 3, further
comprising another detecting means for checking the condition of
the sheets following the side wall sheet aligning operation.
5. A sheet aligning device according to claim 1, wherein the
detecting means comprises first and second detectors which
respectively detect skewing and widthwise displacement of the
sheets relative to the side walls;
said first detector including first and second photoelectric
sensors which respectively include first and second light sources
and first and second light receiving elements, said first light
source and said first receiving element and said second light
source and said second receiving element, respectively, being
arranged in juxtaposed relation;
said second detector including a plurality of photoelectric
sensors, each sensor including a light source and a juxtoposed
light receiving element, said plurality of sensors being located in
a plane perpendicular to the direction in which the sheets are
conveyed.
Description
BACKGROUND OF THE INVENTION
This invention relates to a sheet aligning device having a pair of
side walls located on opposite sides of a multiplicity of
successively fed sheets at least one of which is movable in
reciprocatory movement toward and away from the sheets widthwise
thereof to bring the sheets into alignment with each other in a
direction perpendicular to the direction in which the sheets are
fed.
Copying apparatus, printers or their peripheral devices (such as
automatic document feed devices, sheet folding machines, punching
machines, sheet binding machines, etc.) usually comprise sheet
aligning devices of the type described for aligning copies, printed
sheets, documents and other sheets. In copying apparatus for
copying opposite sides of a document, for example, copy sheets each
having an image of an original formed on one side surface are
placed on a tray of an intermediate sheet feeding device and then
fed again therefrom. In this case, the copy sheets fed to the tray
should be brought into alignment with each other widthwise thereof
in a predetermined position.
The reason why it is necessary to bring the sheets into alignment
with each other by a sheet aligning device is because sheets fed to
a tray, for example, might be displaced, when they are delivered,
from a predetermined position on which they are to be stacked
widthwise of each other (a direction perpendicular to the direction
in which the sheets are fed) with the superposed sheets either
being aligned lengthwise thereof or skewed with respect to the
direction in which they are fed. The widthwise displacement of the
sheets may vary in magnitude depending on the material of the
sheets, their surface smoothness, their size or ambient conditions
(humidity, temperature). Some type of sheets might be displaced
greatly while other type of sheets might not show displacement at
all. The latter type of sheets can be readily handled by a sheet
aligning device. However, difficulties are experienced in bringing
the former type of sheets into alignment with each other.
In sheet aligning devices of the prior art, no consideration has
been paid to the condition of the sheets before they are handled by
the device and it has been customary to move the side walls at a
uniform speed, frequency and stroke in reciprocatory movement in an
attempt to align the sheets with each other. Thus, the devices of
the prior art have suffered the disadvantage that they are unable
to satisfactorily accomplish the object of aligning the sheets when
the magnitudes of their displacements are great. To obviate this
disadvantage, one only has to move the side walls in reciprocatory
movement each time a sheet is fed so that the side walls will
strike one sheet several times, to reduce the speed of movement of
the side walls to facilitate alignment of the sheets or to increase
the stroke of the side walls so that the side walls will shift the
sheets with a greater force, so as to thereby bring the sheets into
alignment with each other even if the magnitudes of their
displacements are great. It will be possible to satisfactorily
align the sheets if the operation is performed over a prolonged
period of time by increasing the frequency of reciprocatory
movement of the side walls or reducing the speed thereof. However,
as noted hereinabove, the magnitudes of displacements of sheets may
vary depending on the material of the sheets and other factors, and
not all the types of sheets are displaced from each other a large
magnitude. Thus, if the sheet aligning operation is performed over
a prolonged period of time by increasing the frequency of
reciprocatory movements of the side walls, a period of time longer
than is necessary would have to be spent in handling sheets which
show little or no displacements. A loss of time would be enormous
when a multiplicity of sheets are handled if the frequency of
movements of the side walls is increased or the time required for
handling each sheet is prolonged. Also, as subsequently to be
described in detail, the intervals at which the sheets are
successively fed should be increased. An apparatus, such as a
printer or a copying apparatus, equipped with this type of sheet
aligning device of the prior art would suffer the disadvantage that
its peripheral equipment is very low in efficiency.
SUMMARY OF THE INVENTION
This invention has been developed for the purpose of obviating the
aforesaid disadvantages of the prior art. Accordingly, the
invention has as one of its object the provision of a sheet
aligning device capable of avoiding a loss of time in achieving
alignment of the sheets without reducing the effects achieved in
bringing them into alignment and performing sheet aligning
operations satisfactorily without increasing the intervals at which
the sheets are fed successively.
Another object is to provide a sheet aligning device capable of
checking the condition in which the sheets have been handled by the
sheet aligning device after a sheet aligning operation has been
performed.
To accomplish the aforesaid objects, the invention provides
outstanding characteristics including detecting means for checking
the condition of sheets before being handled by the sheet aligning
device to detect the sheets at least in one of two conditions
including a widthwise displacement of the sheets which are aligned
lengthwise and a widthwise displacement thereof which are out of
alignment lengthwise, such detecting means producing an output
capable of changing at least one of the frequency, speed and stroke
of the reciprocatory movement of at least one of the side walls
when a sheet aligning operation is performed, and another detecting
means for checking the condition in which the sheets have been
handled by the sheet aligning device to thereby avoid the
disadvantage which might be suffered due to misalignment of the
sheets.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a view in explanation of a copying apparatus for copying
both sides of a document equipped with the sheet aligning device
comprising one embodiment of the invention;
FIG. 2 is a fragmentary sectional plan view of an intermediate
sheet feeding device equipped with the sheet aligning device
according to the invention, with certain parts being removed;
FIG. 3 is a sectional view taken along the line III--III in FIG. 2,
with certain parts being omitted;
FIGS. 4a and 4b are views in explanation of conditions in which
copy sheets are displaced;
FIG. 5 is a view as seen in the direction of arrows V--V in FIG. 1,
in explanation of the first detector of the first detecting
means;
FIG. 6 is a view as seen in the direction of an arrow VI in FIG. 1,
in explanation of the condition of operation of the first detector
shown in FIG. 5;
FIGS. 7 and 8 are views similar to FIGS. 5 and 6 respectively but
showing the second detector of the first detecting means;
FIG. 9 is a view in explanation of the manner in which the side
walls bite into a copy sheet;
FIGS. 10 and 11 are views corresponding to FIGS. 5 and 6
respectively but showing the second detecting means;
FIG. 12 is a sectional view similar to FIG. 3 but taken along the
line XII--XII in FIG. 2;
FIGS. 13 and 14 are plan views in explanation of the relation
between the length of a copy sheet and the side walls;
FIG. 15 is a plan view similar to FIG. 2 but showing the third
detecting means, with a sheet aligning operation being performed
while the guide rods are removed;
FIG. 16 is a plan view similar to FIG. 15 but showing the condition
in which the copy sheets are misaligned;
FIG. 17 is a sectional view of the third detecting means;
FIG. 18 is a sectional view of a modification of the third
detecting means shown in FIG. 17;
FIG. 19 is a perspective view of another modification of the third
detecting means shown in FIG. 17;
FIG. 20 is a plan view of the sheet aligning device comprising
another embodiment in which compression spring and support plates
are used to support the side walls for moving same to align the
sheets;
FIG. 21 is a plan view of the sheet aligning device comprising
still another embodiment in which a slanting roller is used for
exerting on a sheet a force oriented in a direction skewed with
respect to the direction in which the sheet is fed;
FIG. 22 is a fragmentary perspective view of the intermediate sheet
feeding device cooperating with the sheet aligning device according
to the invention, with certain parts being shown in phantom
lines;
FIGS. 23-28 are views in explanation of the operation of the sheet
aligning device, with the guide rods and other parts being removed;
and
FIG. 29 is a sectional view taken along the line XVIII--XVIII in
FIG. 27.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Preferred embodiments of the invention will now be described by
referring to the accompanying drawings.
To enable the present invention to be fully understood, the
construction of a copying apparatus for copying both side surfaces
of a document on opposite surfaces of copy sheets will be described
in a sectional view shown in FIG. 1.
The copying apparatus shown in FIG. 1 comprises a main body 1
having a contact glass member 2 secured to its top surface to have
a document 3 placed thereon. The operator selects a both-surfaces
copying mode and depresses a copy button, not shown, to move a
light source 4 from the illustrated position rightwardly in FIG. 1.
At this time, a light beam emanating from the light source 4
illuminates a top surface of the document 3 before the light source
4 is restored to its original position. The top surface of the
document 3 illuminated by the light beam from the light source 4
reflects the light beam through an image forming optical system 5
comprising mirrors and lenses to expose a photosensitive member 6
rotating counter-clockwise to an optical image of the document 3,
to thereby form an electrostatic latent image on a surface of the
photosensitive member 6 which is developed into a visible image
with a toner.
Meanwhile, a sheet 8 fed from a main sheet feeding device 7 is fed
to a predetermined position in which the sheet 8 is indexed with
the electrostatic latent images as it is delivered to the
predetermined position in a transfer-printing station where the
toner image on the photosensitive member 6 is printed by
transfer-printing on a surface of the sheet 8. The sheet 8 having
the toner image (visible image) of the document 3 on one surface
thereof is passed through a fixing device 9 to have the image fixed
on the sheet 8, to provide a one-surface copy sheet which is
switched back as indicated by arrows A and B by an inverting device
10 after being released from the fixing device 9 and fed into a
tray 12 of an intermediate sheet feeding device 11 as indicated by
an arrow E.
The operation described hereinabove is repeatedly performed, and
one-surface copy sheets are fed successively into the tray 12 at
intervals. As the one-surface copy sheets 8 form a stack on the
tray 12 in a predetermined number as indicated by two-dots between
two-dashed lines, a sheet feeding roller 13 is brought into contact
with the topmost sheet 8 and rotated clockwise to thereby feed one
sheet after another to the transfer-printing station to have an
image of the document 3 printed on an opposite side surface and
fixed by the fixing device 9, before being discharged from the main
body 1 as indicated by an arrow D onto a stacker 14.
As described hereinabove, the copy sheets 8 are successively placed
on the tray 12 and temporarily stacked thereon. If the copy sheets
8 stacked on the tray 12 are misaligned, trouble would occur and
the copy sheet might be brought out of index with the visible or
toner image on the surface of the photosensitive member 6 when
delivered to the predetermined position in the transfer-printing
station. To avoid this trouble, a sheet aligning device 15
according to the invention is mounted in association with the tray
12 so as to align the copy sheets 8 widthwise thereof.
FIG. 2 shows one embodiment of the sheet aligning device 15 in
conformity with the invention comprising a pair of side walls 16
and 17 located on opposite lateral sides of the copy sheets 8
delivered to the tray 12. As shown in FIGS. 2, 3 and 12, the side
walls 16 and 17 have bases 16a and 17a, respectively, which are
fitted in a cutout 18 formed in the tray 12 and supported for
movement in a direction F widthwise of the copy sheets 8 which is
perpendicular to the direction E in which the copy sheets 8 are
delivered to the tray 12. The side walls 16 and 17 are driven by a
drive unit subsequently to be described to move toward and away
from each other while being maintained in positions which are
symmetrical with respect to a center reference line G between
them.
As a copy sheet 8 is delivered to the tray 12, the side walls 16
and 17 are disposed in standby or inoperative positions shown in
solid lines in FIG. 2 in which the spacing between them is greater
than the width W of the copy sheet 8 so as to avoid the trouble
that the copy sheet 8 might otherwise impinge on the side walls 16
and 17 and be prevented from entering the space defined
therebetween.
The sheet aligning operation performed by the side walls 16 and 17
is as follows: The side walls 16 and 17 disposed in the standby or
inoperative positions begin to move toward each other after the
copy sheet 8 delivered in the direction of the arrow E has entered
the space between them or immediately before entering the space
between them. In the embodiment shown and described herein, the
side walls 16 and 17 begin to move toward each other after a
leading edge 8e of the copy sheet 8 impinges on a front striking
bar 19 secured to a front edge of the tray 12 (on the left side in
FIG. 2) and the copy sheet 8 is brought to a halt. The side walls
16 and 17 moving toward each other impinge on opposite lateral
sides 8a and 8b of the copy sheet 8 respectively as shown in
two-dots between two-dashed lines in FIG. 2 and then move away from
each other back to the inoperative positions shown in solid lines.
As the side walls 16 and 17 move in reciprocatory movement toward
and away from the copy sheet 8 on the tray 12, the copy sheet 8 is
brought to a position on the tray 12 in which a lengthwise center
line of the copy sheet 8 perpendicular to the width F thereof is in
alignment with the center reference line G between the side walls
16 and 17.
The reason why it is necessary to align the copy sheets 8 widthwise
thereof F is because the copy sheets 8 delivered to the tray 12 are
sometimes displaced or slanting widthwise thereof. FIG. 4a shows
the copy sheet 8 displaced upwardly widthwise F in FIG. 4a although
its lengthwise center line H perpendicular to the width F is
parallel to the center reference line G. FIG. 4b shows the copy
sheet 8 slanting or skewed with respect to the direction E in which
it is delivered to the tray 12. As shown, a lateral side edge of
the copy sheet 8 connecting a corner 8c at a leading edge and a
corner 8d at a trailing edge together is slanting by a magnitude S
with respect to the center reference line G. FIGS. 4a and 4b merely
show the positions of the copy sheet for purposes of illustration,
and in actual practice, the copy sheet 8 may be disposed in any
other position. The direction in which the copy sheet 8 might be
displaced and the magnitudes L and S of the displacements may vary
depending on the material and size of the copy sheet 8 and the
environmental condition under which copying operation is performed.
In the prior art, it has been usual practice to move the side walls
16 and 17 at a standardized frequency, speed and stroke. This has
given rise to the disadvantage that the copy sheets have not been
aligned satisfactorily or a period of time longer than is necessary
is required to perform sheet aligning operations, as noted
hereinabove.
In the aligning device 15 shown, the magnitudes L and S of the
displacements of the sheet 8 are detected by detecting means and
the side walls 16 and 17 are moved in reciprocatory movement with a
frequency, at a speed or with a stroke commensurate with the output
of the detecting means or the magnitudes of displacements of the
sheet 8, so that the effects of aligning the sheets 8 can be
satisfactorily achieved while avoiding waste of time.
FIG. 1 shows detecting means 20 comprising a first detector 21 and
a second detector 22 located in suitable position upstream of the
sheet aligning device 15 with respect to the direction in which the
sheets 8 are conveyed, or between the reversing device 10 and
intermediate sheet feeding device 11. Alternatively, the detecting
means 20 may be located in the position in which the sheet aligning
device 15 is located.
The first detector 21 which detects skewing of the sheets 8
includes a photoelectric sensor composed of a first light source 23
and a first light receiving element 24 juxtaposed against each
other, and another photoelectric sensor composed of a second light
source 23a and a second light receiving element 24a juxtaposed
against each other, as shown in FIGS. 5 and 6. The sheets 8 pass
between the light sources 23 and 23a and the light receiving
elements 24 and 24a. As shown in FIG. 6, the first light source and
light receiving elements 23 and 24 and the second light source and
light receiving element 23a and 24a are located in a plane I
perpendicular to the direction E in which the sheets 8 are
conveyed.
Assume that the sheet 8 is skewed with respect to the direction E
in which the sheet 8 is conveyed and the skew of a lateral side of
the sheet 8 connecting corners 8c and 8d together with respect to
the direction E has a magnitude S, as shown exaggeratedly in FIG.
6. When the leading edge 8e of the sheet 8 reaches the detector 21,
the sheet 8 first intercepts a light beam directed from the second
light source 23a against the second light receiving element 24a as
indicated by a solid line in FIG. 6, thereby keeping the light beam
from being incident on the second light receiving element 24a.
After a lapse of a certain period of time, the sheet 8 intercepts a
light beam directed from the first light source 23 against the
first light receiving element 24, as shown by two-dots between
two-dashed lines in FIG. 6, thereby keeping the light beam from
being incident on the first light receiving element 24. As
described hereinabove, if the sheet 8 is skewed, there is a lag of
the time at which the light beam incident on the first light
receiving element 24 is intercepted behind the time at which the
light beam incident on the second light receiving element 24a is
intercepted. Let the time lag be denoted by .DELTA.T. The speed at
which the sheets 8 are conveyed being substantially constant and
the length l of the sheet 8 being known, it is possible to
determine the magnitude S of the skew by detecting the time lag
.DELTA.T. The length l of the sheets 8 may be detected each time
copying operation is performed by sensing means, not shown, of any
known type.
The second detector 22 which detects a displacement of the sheet 8
widthwise F thereof with its length remaining parallel to the
center reference line G includes a plurality of photoelectric
sensors composed of a plurality (eight in the embodiment shown) of
light sources 25-32 and a plurality (eight in the embodiment shown)
of light receiving elements 33-40 disposed in juxtaposed relation
to the respective light sources which are located in a plane J
perpendicular to the direction E in which the sheets 8 are
conveyed, as shown in FIGS. 7 and 8. When the sheet 8 is not
displaced widthwise F at all as indicated by broken lines in FIG.
8, light beam directed from a predetermined number of light source
or four light sources 29, 30, 31 and 32 in this embodiment against
a predetermined number of light receiving elements or four light
receiving elements 37, 38, 39 and 40 in this embodiment juxtaposed
against the respective light sources are intercepted, so that the
light beams from these light sources are kept from being incident
on the respective light receiving elements. However, light beams
directed from other light sources 25, 26, 27 and 28 remain incident
on the respective light receiving elements 33, 34, 35 and 36. If
the sheet 8 is displaced widthwise by a magnitude L while its
length remains parallel to the center reference line G as indicated
by solid lines in FIG. 8, the number of light sources and light
receiving elements having light beams intercepted by the sheet 8
will increase or decrease. In the embodiment shown in FIG. 8, the
light beams directed from the light sources 31 and 32 against the
light receiving elements 39 and 40 respectively are intercepted
while the light beams directed from the light sources 25-30 against
the light receiving elements 33-38 respectively remain incident
thereon. Thus, it is possible to determine the magnitude L of the
displacement of the sheet 8 by using as a reference the number of
light receiving elements prevented from receiving light beams from
the respective light sources when the sheet 8 shows no displacement
and determining the difference between the reference number and the
actual number of light receiving elements having light beams
prevented from being incident thereon by the sheet 8.
The magnitudes L and S of the displacements of the sheet 8 can be
determined as described hereinabove. If one or both of the
magnitudes L and S rise above predetermined levels, the side wall
actuating device is controlled such that the frequency of
reciprocatory movements of the side walls 16 and 17 of the sheet
aligning device 15 is increased, their speed is reduced or their
stroke is increased.
By reducing the speed at which the side walls 16 and 17 is moved in
reciprocatory movement, it is possible to positively achieve the
sheet aligning effect, because application of an impact of high
external force by the walls 16 and 17 on the sheet 8 can be avoided
and the danger of the sheet 8 buckling or being repulsed by the
walls 16 and 17 is prevented, even if the magnitude of the
displacement is great. Also, by increasing the stroke of the side
walls 16 and 17 in such a manner that, as shown in FIG. 9, the
spacing interval between the side walls 16 17 is smaller than the
width W of the sheet 8 having no external force exerted thereon
when the spacing interval is minimized and that the side walls 16
and 17 bite into the sheet 8 by a magnitude K, it is possible to
achieve the sheet aligning effect because the sheet 8 is strongly
held down by the side walls 16 and 17. When the sheet 8 moves into
the space between the side walls 16 and 17, they are disposed in
inoperative positions. However, when the magnitudes L and S of the
displacements of the sheet 8 are particularly great, the leading
edge 8e of the sheet 8 might impinge on the side walls 16 and 17
even if they are disposed in the inoperative or standby positions
indicated by solid lines in FIG. 2. Thus, by increasing the stroke
of the reciprocatory movements of the side walls 16 and 17 in such
a manner that the side walls 16 and 17 move to broken line
positions shown in FIG. 2 which are spaced apart a greater distance
from each other than the solid line positions it is possible to
avoid the impinging of the sheet 8 on the side walls 16 and 17,
thereby positively achieving the sheet aligning effect. The sheet
aligning effect can be achieved by increasing the frequency with
which the side walls 16 and 17 are moved in reciprocatory movement.
More specifically, if the side walls 16 and 17 are moved in
reciprocatory movement each time one sheet 8 or a small number of
sheets 8 (two or three, for example) are fed into the tray 12 or if
the side walls 16 and 17 are moved in a plurality of reciprocatory
movements to cope with one sheet 8, it is possible to positively
bring the sheet into alignment with the center reference line G
even if the displacement of the sheet 8 is great in magnitude. It
will be appreciated that when a large number of sheets are brought
into alignment with each other, it is easier to handle a small
number of sheets several times than to handle the large number of
sheets at a time. The side wall actuating device can be
advantageously controlled if the frequency, speed and stroke of the
reciprocatory movements of the side walls 16 and 17 are adjusted in
accordance with the magnitudes L and S of the displacement of the
sheet 8 in such a manner that the frequency is increased, the speed
is reduced and the stroke is increased when the displacement is
great in magnitude.
In the embodiment shown and described, when the sheet 8 handled is
of A4 size, the spacing l.sub.1 between the side walls 16 and 17 in
the inoperative positions shown in solid lines and the lateral
sides 8a and 8b of the sheet 8, as shown in FIG. 2, is about 11 mm.
When at least one of the magnitudes L and S of the displacements of
the sheet 8 has a value of about 3 mm.+-.0.5 mm, the side wall
actuating device is controlled in such a manner that the side walls
16 and 17 are moved in one reciprocatory movement, the stroke of
the reciprocatory movement is set at a value obtained by adding
about 4 mm to the aforesaid magnitude K or about 15 mm, and the
speed of the reciprocatory movement is set at a speed which would
enable the distance of about 15 mm to be covered in about 0.13
second.
Thus, in the embodiment shown and described, the side wall
actuating device is controlled in such a manner that when the
predetermined value of the magnitudes L and S of the displacement
of the sheet 8 is set at about 3 mm.+-.0.5 mm, the side walls 16
and 17 are moved in reciprocatory movement a plurality of number of
times, or the speed of the reciprocatory movements is reduced, or
the stroke of the reciprocatory movements is increased, if at least
one of the magnitudes L and S exceeds the predetermined value.
By controlling the movements of the side walls 16 and 17 as
described hereinabove, it is possible to bring the sheets 8 into
alignment with each other widthwise thereof to such a degree that
further movement of the sheets 8 is not interfered with, even if
the magnitudes L and S of the displacements of the sheets 8 are
great.
Conversely, when the magnitudes L and S are smaller than the
predetermined values, the movements of the side walls 16 and 17 are
controlled such that the frequency of movements of the side walls
16 and 17 is reduced, the speed of movements is increased and the
stroke of the movements is reduced. To reduce the stroke, one only
has to set the inoperative positions of the side walls 16 and 17 at
the solid line positions shown in FIG. 2 or set at positions nearer
to the sheet 8, or one only has to reduce the magnitude of the side
walls 16 and 17 biting into the sheet 8 as shown in FIG. 9 or
eliminate the biting of the side walls 16 and 17 into the sheet 8.
This does not necessarily reduce the effects achieved by the sheet
aligning device 15 because the sheets 8 with a small magnitude L or
S of displacements are essentially easy to align. Moreover, if the
frequency of the reciprocatory movements of the side walls is
reduced, their speed is increased and their stroke is reduced, then
it is possible to reduce the time required for performing a sheet
aligning operation and reduce the intervals at which the sheets 8
are successively fed to the photosensitive member 6. This advantage
will be described in more detail.
Assume that the side walls are actuated to perform a sheet aligning
operation when one sheet is fed to the photosensitive member 6, and
that the next following sheet is fed to the photosensitive member 6
while the spacing interval between the side walls is still small.
Then, there is the danger that the leading edge of the next
following sheet would impinge on the side walls. To avoid this
trouble, in the illustrated embodiment, the spacing interval
between the side walls is greater than the width W of the sheet
before the sheet enters the space defined between the side walls,
and the next following sheet is allowed to enter the space between
the side walls after the operation of bringing the preceding sheet
into alignment with the center reference line G is finished. Thus,
if a prolonged period of time is required for the side walls 16 and
17 to complete one reciprocatory movement, then it is necessary to
increase the intervals at which the sheets are successively fed to
the photosensitive member 6 to keep the leading edge of each
successively fed sheet 8 from impinging on the side walls 16 and
17. However, in the embodiment of the illustrated construction,
when the magnitudes L and S of the displacements of the sheet 8 are
small, it is possible to reduce the period of time for the side
walls 16 and 17 to move in one reciprocatory movement by increasing
the speed of movements of the side walls and reducing their stroke.
Thus, the trouble of the leading edge of the sheet impinging on the
side walls can be avoided even if the intervals at which the sheets
are fed is rather reduced, as contrasted with the operation in
which it takes a prolonged period of time for the side walls to
move in reciprocatory movement to cope with sheets having large
magnitudes L and S of displacements. When the magnitudes L and S
are small, the frequency of reciprocatory movements of the side
walls 16 and 17 may be reduced in such a manner that a sheet
aligning operation is performed each time about ten (10) sheets are
fed to the tray 12, for example. This would make it possible to
increase as much as necessary the interval at which the sheet
following the sheet being aligned by the side walls 16 and 17 while
minimizing the intervals at which the following sheets are fed. By
reducing the intervals at which the sheets are fed, it is possible
to reduce the time necessary for a predetermined number of sheets
to be processed or increase the copying speed.
In the sheet aligning device 15 of the aforesaid construction, the
side wall actuating device is controlled to cause the side walls 16
and 17 operate differently in accordance with the magnitudes L and
S of the displacements of the sheets 8, so as to set the intervals
at which the sheets 8 are fed successively according to the
magnitudes L and S. More specifically, the intervals are increased
when the magnitudes L and S are great to enable alignment of sheets
to be positively obtained, and reduced when the intervals are small
to increase the speed at which copying is performed. Thus, it is
necessary to alter the intervals each time a copying operation is
performed. The end can be attained by controlling in accordance
with the output of the detecting means 20 the timing with which the
light source 4 shown in FIG. 1 is moved rightwardly from the
illustrated position. More specifically, when it is found by the
detecting means 20 that the magnitudes L and S are great and it is
necessary to increase the intervals, control is effected such that
the time at which the light source 4 begins to move is delayed by
the output of the detecting means 20 so as to match the timing with
which the sheets 8 are fed to the photosensitive member 6 to the
timing with which the movement of the light source 4 is begun.
Conversely, when it is desired to reduce the intervals, control is
effected such that the time at which the light source 4 begins to
move is hastened and the sheets 8 are fed to the photosensitive
member 6 with a timing matching the timing with which the light
source 4 begins to move.
However, if the time at which the light source 4 begins to move is
controlled as aforesaid while the detecting means 20 is located in
the illustrated position in FIG. 1, the problem described
hereinafter might be raised That is, after the copying operation is
started, the magnitudes L and S are not determined until the first
sheet 8 reaches the detecting means 20. However, when the first
sheet 8 reaches the detecting means 20, the light source 4 has
already completed at least one reciprocatory movement. Thus, it
would be impossible to control the timing with which the movement
of the light source 4 is initiated in accordance with the
magnitudes L and S.
When sheets 8 of a certain type are placed in the main sheet
feeding device 7 prior to the initiation of a copying operation,
the size, thickness and quality of the sheets 8 are known and
substantially constant. Thus, the magnitudes L and S of the
displacements of the sheets 8 are usually substantially constant
when they are successively fed and pass through the detecting means
20. In view of the foregoing, control may be effected as follows.
Until the first sheet 8 reaches the detecting means 20 and the
magnitude L or S is detected, the intervals are increased to allow
the sheets 8 to be readily aligned with each other no matter how
large the magnitude may be. The frequency with which the side walls
16 and 17 are moved in reciprocatory movement is increased, the
stroke of their movements is increased and the speed of their
movements is reduced to positively bring the sheets 8 into
alignment with each other. After the magnitude of a displacement of
the first sheet 8 is detected, the timing with which the movement
of the light source 4 is initiated is controlled in accordance with
the magnitude of the displacement or the output of the detecting
means, to set the intervals at a suitable level and control the
frequency, speed and stroke of the reciprocately movements of the
side walls 16 and 17 accordingly. By effecting control as described
hereinabove, it is possible, although a period of time longer than
is necessary might be required for handling the first sheet and a
few sheets following the first sheet, to bring the rest of the
sheets into alignment with each other in a suitable period of time.
Meanwhile, the number of sheets on which toner images are formed
before the magnitude of a displacement of the first sheet is
detected is usually very small, and a small number of sheets can be
usually brought into alignment with each other with ease. Thus, no
great trouble occurs by making an arrangement whereby the intervals
at which sheets are fed are rather reduced before the magnitude of
the displacement of the first sheet is detected in performing sheet
aligning, and the timing with which the movement of the light
source 4 is initiated is only controlled after the magnitude of the
displacement of a sheet is detected.
By setting the position of the detecting means in such a manner
that the magnitudes of the displacement of a sheet can be detected
before the sheet reaches the photosensitive member 6 before being
fed from the main sheet feeding device 7, it is possible to control
the timing with which the movement of the light source 4 is
initiated to enable all the sheets to be fed at suitable intervals.
However, if the detecting means is located in the aforesaid
position, the sensing means would be spaced apart from the tray 12
a great distance. This would make it necessary to determine the
magnitude of the displacement of a sheet by taking into
consideration the magnitude of a displacement of the sheet that
would occur between the detecting means and the tray 12.
The actuating device for moving the side walls 16 and 17 in
reciprocatory movement comprises, as shown in FIGS. 2, 3 and 12,
guide rods 41 extending widthwise F through a lower portion of the
tray 12, on which the side walls 16 and 17 are fitted for sliding
movement widthwise of the sheet 8. One side wall 16 is secured in a
position 16b to one run 42a of an endless chain 42 trained over a
drive sprocket wheel 43 and a follower sprocket wheel 44, and the
other side wall 17 is secured in a position 17b to an opposite run
42b of the endless chain 42. The drive sprocket wheel 43 is driven
for rotation by a steppling motor, not shown, which rotates in
accordance with the number of inputted pulses, to move the runs 42a
and 42b of the endless chain 42 in opposite directions to thereby
move the side walls 16 and 17 toward and away from each other. The
invention is not limited to the stepping motor, and other known
motor or drive means may be used. The actuation of the side walls
16 and 17 is controlled as described hereinabove. The distance
covered by the movement of the side walls to the phantom line
postions shown in FIG. 2 may vary depending on the width W of the
sheets. To cope with this situation, control may be effected such
that a central processing unit is provided to regulate the rotation
of the stepping motor or clutch or speed change gearing located
between the motor and side walls is actuated. The timing with which
the movement of the light source 4 is initiated may be controlled
readily by using a central processing unit.
The basic constructional form of the sheet aligning device
according to the invention has been described by referring to the
accompanying drawings. However, many changes and modifications may
be made therein. For example, the actuating device for moving the
side walls may comprise a rope and pulleys, in place of the endless
chain and the sprocket wheels. Alternatively, a feed screw driven
for rotation and a nut threadably engaging the feed screw and
moving therewith as a unit may be used. Other known means may, of
course, be used. In place of moving the opposite side walls in
reciprocatory movement and bringing the sheets into alignment with
the center reference line G, one side wall 16 shown in FIG. 2 may
be made movable but the other side wall 17 may be made immovable,
thereby allowing only the one side wall 16 to move in reciprocatory
movement when a sheet aligning operation is performed. If only one
side wall is moved, it is possible to align the sheets with each
other by using the position of the immovable side wall as a
reference (one side reference).
The invention is not limited to the detecting means of the type
described. For example, means for detecting the magnitudes of the
displacements of sheets may comprise a photoelectric sensor
including a light source 50 and a light receiving element 51
located in spaced juxtaposed relation on opposite sides of the
sheet 8 and another photoelectric sensor including a light source
50a and a light receiving element 51 a located in spaced juxtaposed
relation on opposite sides of the sheet 8 as shown in FIG. 10. The
two photoelectric sensors 50, 51 and 50a, 51a are spaced apart a
small distance .DELTA.L widthwise F of the sheet 8, as shown in
FIG. 11. When the sheet 8 is not displaced withdthwise F as
indicated by solid lines, a light beam directed from the light
source 50a against the light receiving element 51a is intercepted
by the sheet 8 while a light beam directed from the light source 50
against the light receiving element 51 is incident thereon. When
the displacement of the sheet 8 widthwise F thereof is great in
magnitude as indicated by phantom lines in FIG. 11, the light beams
directed from the light sources 50 and 50a against the light
receiving elements 51 and 51a respectively are both intercepted by
the sheet 8 or not intercepted thereby entirely. This indicates
that the copy sheet 8 is displaced widthwise F although it remains
in alignment with the center reference line G. By setting the
magnitude of .DELTA.L at a suitable level, it is possible to alter
the reference for determining whether or not the sheet remains
parallel with other sheets although it is displaced widthwise
F.
By using the detecting means shown in FIGS. 7 and 8, it is possible
to determine the slanting or skew of a sheet 8. More specifically,
when the sheet 8 is skewed, the time at which the light beam of the
light source of one photoelectric sensor incident on the light
receiving element thereof is intercepted by the sheet will show a
lag behind the time at which the light beam of the light source of
another photoelectric sensor incident on the light receiving
element thereof is intercepted in the same manner as described by
referring to the detecting means shown in FIGS. 5 and 6. Thus, by
detecting the time lag, it is possible to determine the skew of the
sheet 8. If the skew of the sheet 8 is detected while the
displacement of the sheet 8 widthwise F thereof although remaining
in alignment with the center reference line G is also detected,
then it is possible to detect both the skew and the displacement of
the sheet 8 widthwise F thereof while remaining in alignment with
the center reference line G by using only the detecting means shown
in FIGS. 7 and 8.
When the sheets 8 are conveyed in accordance with the center
reference and brought into alignment with the center reference line
G at the tray 12, as is the case with the embodiment shown in FIG.
2, it might be impossible to detect displacements of sheets 8 by
the detecting means shown in FIGS. 7 and 8 and 10 and 11, when the
sheets 8 show a difference in width W. Displacements of sheets 8
can be detected without any difficulty if the sensing means is
shifted widthwise F in conformity with the width W. When sheets 8
are conveyed in accordance with one-side reference and aligned
according to one-side reference, it is possible to detect the
magnitudes of displacements even if the detecting means remains
immovable. The detecting means shown in FIGS. 5 and 6 is capable of
detecting the magnitudes of displacements without moving its
position, regardless of whether the reference is center reference
or one-side reference.
The same results can be achieved by using detecting means relying
on other means than the photoelectric sensors.
In the embodiment shown and described, both the skewing and
displacing of sheets 8 widthwise thereof while remaining in
alignment with the reference line are detected. However, either the
skewing or the displacement of sheets while remaining parallel to
the reference line may be detected by the detecting means and at
least one of the frequency, speed and stroke of the reciprocatory
movements of the side walls 16 and 17 may be controlled in
accordance with the output of the detecting means, to accomplish
the objects of the invention.
Although it is not directly related to the displacement of a sheet,
the length of the sheet aligned with the direction in which the
sheet is conveyed is an important factor concerned in the
determination of the intervals at which a plurality of sheets are
successively fed to the photosensitive member 6. The invention will
be described by referring to the embodiment shown and described
hereinabove with regard to the length of sheets.
Referring to FIGS. 13 and 14, assume that the sheets 8 are fed
successively at intervals P to a space defined between the side
walls 16 and 17. The intervals P are set in such a manner that the
leading edge 8e of the next following sheet 8 (the sheet on the
right side in the figure) does not impinge on the side walls 16 and
17. When the length M of the sheets 8 aligned with the direction E
in which they are fed is great as shown in FIG. 13, the distance
Q.sub.1 between right ends of the side walls 16 and 17 and the
leading edge 8e of the next following sheet 8 is greater, as the
preceding sheet 8 is disposed in the space between the side walls
16 and 17, than the distance Q.sub.2 between the right ends of the
walls 16 and 17 and the leading edge 8e of the next following sheet
8 when the length N of the sheets 8 is small as shown in FIG. 14.
Thus, the speed at which the sheets 8 are conveyed being constant,
the greater the length of the sheets 8, the longer is the time that
elapses after the preceding sheet 8 has reached the space between
the side walls 16 and 17 until the next following sheet 8 reaches
the right ends of the side walls 16 and 17. Stated differently, if
the sheets 8 have a great length, it is possible for the side walls
16 and 17 to take a longer time to move in reciprocatory movement
between inoperative and operative positions than if they have a
short length, thereby making it possible to increase the frequency
of the reciprocatory movements and increase their stroke while
reducing their speed. It has been described hereinabove that when
the magnitudes L and S of the displacements of the sheets 8 are
great, the frequency of the reciprocatory movements of the side
walls 16 and 17 is increased and the time required for handling
each sheet 8 is prolonged. In this case, when the sheets 8 have a
great length, it is possible to avoid the danger of the leading
edge of the next following sheet 8 impinging on the side walls 16
and 17 can be avoided without requiring to increase the intervals
at which the sheets 8 are fed to the photosensitive member 6. Thus,
the frequency, stroke and speed of the reciprocatory movements of
the side walls 16 and 17 are preferably controlled by detecting the
length of the sheets 8 by known detecting means or setting the
apparatus to the specific length by depressing a key on the
operation panel of the main body of the apparatus in addition to
detecting the displacements of the sheets 8 widthwise thereof.
Usually, some sheets are easy to align and others are difficult to
attain the end of bringing them into alignment with each other.
This is attributed to the nature of the sheets or the rigidity,
thickness, surface smoothness, weight and size of the materials of
the sheets and environmental factors including temperature and
humidity. The sheets listed hereinafter are hard to align.
1. Nature of Sheets
Sheets of large width, large thickness, low rigidity, light weight
and high frictional dragging on each other.
2. Environmental Factors
High humidity (the sheets absorb moisture and become lower in
rigidity), and high temperature (although the results achieved may
vary depending on the quality of material, the sheets become harder
to align when ambient temperature rises in most cases).
3. Other Factors
When the fixing device relies on thermal fixing, the sheets become
harder to align when the heat used for thermal fixing is high in
temperature because of the increased tendency of the sheets to
curl.
The sheets which do not belong to the aforesaid groups are easy to
align.
In the prior art, the aforesaid factors tending to influence the
ease with which the sheets are aligned have not been taken into
consideration in controlling the actuating device for moving the
side walls 16 and 17 by changing the frequency, stroke and speed of
the reciprocatory movements of the side walls 16 and 17. This has
often resulted in being unable to achieve unsatisfactory results in
aligning the sheets 8 or taking more time than is necessary to
perform sheet aligning.
According to the invention, these disadvantages of the prior art
are obviated by taking at least one of the aforesaid factors into
consideration and moving the side walls 16 and 17 with a frequency
suiting the particular condition, at a speed suiting the particular
condition or at a stroke suiting the particular condition, so that
satisfactory results can be achieved in bringing the sheets 8 into
alignments with each other or the waste of time can be avoided in
performing a sheet aligning operation.
More specifically, in the embodiment shown and described
hereinabove, the actuating device for moving the side walls 16 and
17 is controlled, when at least one of the aforesaid factors
concerned in making it difficult to align the sheets 8 exists, in
such a manner that the frequency of the reciprocatory movements of
the side walls 16 and 17 is increased, their speed is reduced, or
their stroke is increased.
Conversely, when the sheets 8 are of the nature or under the
conditions making it easier to bring them into alignment, the
frequency of the reciprocatory movements of the side walls 16 and
17 is reduced, their speed is increased or their stroke is
reduced.
As described hereinabove, the sheets 8 are brought into alignment
with each other by the sheet aligning device 15. When the sheets 8
have a large volume of static buildup, are damaged, are greatly
curled or are low in rigidity, the precision with which they are
aligned might be reduced due to the lateral sides 8a and 8b of each
sheet 8 being pressed back by the side walls 16 and 17,
respectively. In FIGS. 16 and 17, a sheet 8 disposed in a
predetermined postion, a sheet 8 of low aligning precision which is
biased toward the side wall 17 and a sheet 8 of low aligning
precision which is biased toward the side wall 16 are designated by
dot-and-dash lines, two-dots between two-dashed lines and broken
lines, respectively. If the copy sheets 8 which are not disposed in
the predetermined postion on the tray 12 are fed to the
photosensitive member 6, it would be impossible to bring them into
index with a predetermined zone on the photosensitive member 6 in
the printing station, so that a developed image would be formed in
a position on the sheet which is displaced from the predetermined
position. Also, a jamming of the sheets might occur when they are
fed from the irregular positions on the tray 12.
In the invention, the sheet aligning device 15 further comprises
third detecting means 70 shown in FIGS. 15-17 which checks on the
sheet 8 after being subjected to the sheet aligning operation by
the side walls 16 and 17. The detecting means 70 comprises a
plurality (nine in this embodiment) of light sources 71-79 arranged
widthwise F of the sheet 8 in positions above the tray 12, and a
plurality (nine in this embodiment) of light receiving elements
71a-79a arranged widthwise F of the sheet 8 in positions below the
tray 12, so that each light source and light receiving element pair
constitutes a photoelectric sensor. As shown in FIG. 17, light
beams from the light sources 71-79 are incident on the respective
light receiving elements 71a-79a as indicated by phantom lines
through a light opening 12a formed in the tray 12.
When the sheet 8 aligned by the side walls 16 and 17 is disposed in
the predetermined position as indicated by dash-and-dot lines in
FIGS. 16 and 17, the light beams directed from the predetermined
number of light sources selected in accordance with the width W of
the sheet 8 or five light sources 75-79 in the embodiment shown
against the respective light receiving elements 75a-79a are
intercepted by the sheet 8 while the light beams directed from
other light sources or 71-74 against the respective light receiving
elements 71a-74a are allowed to be incident thereon. When the sheet
8 handled by the side walls 16 and 17 is not disposed in the
predetermined position on the tray 12, the number of light sources
whose light beams are intercepted by the sheet 8 increases or
decreases. For example, when the sheet 8 handled by the side walls
16 and 17 is disposed such that its lateral side 8b is disposed
outwardly of the lateral side 8b in the predetermined position by a
distance L.sub.1 as indicated by two-dots between two-dashed lines
in FIGS. 16 and 17, the seven light beams directed from the light
sources 73-79 against the respective light receiving elements
73a-79a are intercepted by the sheet 8. When the sheet 8 handled by
the side walls 16 and 17 is disposed in the position indicated by
the broken lines in FIGS. 16 and 17 in which the lateral side 8b is
disposed inwardly of the predetermined position of the lateral side
8b by a distance L.sub.2 as indicated by broken lines, the light
beams directed from the two light sources 78 and 79 against the
respective light receiving elements 78a and 79a are intercepted by
the sheet 8. Thus it will be possible to determine how the sheets 8
have been handled by the side walls 16 and 17 by counting the
number of light receiving elements on which no light beams are
incident and comparing the number obtained with the number of light
receiving elements on which no light beams are incident when the
sheet 8 is disposed in the predetermined position which serves as a
reference number.
Detecting means 70a similar to the detecting means 70 described by
referring to FIGS. 16 and 17 may be mounted in the vicinity of the
lateral side 8a of the sheet 8 as shown in FIGS. 15 and 16.
The results achieved by the aligning device 15 can be checked as
described hereinabove. When the sheets 8 handled by the side walls
have not been properly aligned, the following steps may be
taken:
(a) When the sheets 8 are misaligned, the magnitudes L.sub.1 and
L.sub.2 of the displacements of the sheets may be indicated by an
indicator of the main body of the copying apparatus by digital
display in accordance with the output of the third detecting means
and at the same time transmitted to the operator; and
(b) When the magnitudes L.sub.1 and L.sub.2 of the displacements
have exceeded the predetermined levels, indication may be given by
means of a warning device (lamp, buzzer, etc.) mounted in the main
body of the copying apparatus and at the same time the information
may be transmitted to the operator.
The indication may be given each time misalignment occurs during
the period of time the sheets 8 are successively conveyed to the
tray 12 or at a time after a predetermined number of sheets 8 have
been stacked on the tray 12. In the latter case, the results
achieved by the sheet aligning device 15 may be checked only after
the predetermined number of sheets 8 have been stacked on the tray
12. When the indication is given while the sheets are being
conveyed to the tray 12, the operator may render the copying
apparatus inoperative and restart the copying operation by
depressing the print key after manually bringing the sheets 8 into
alignment. Alternatively, the operation of the copying apparatus
may be automatically interrupted by the output of the detecting
means. When the indication is given after all the sheets 8 have
been stacked on the tray 12, the sheets can be brought into
alignment after completion of the stacking of all the sheets 8 on
the tray 12. The condition of misalignment of the sheets 8 that can
be tolerated may usually differ from one operator to another. When
a slight displacement of an image formed on a sheet is tolerated,
no problem is raised even if the sheets on the tray 12 are somewhat
out of alignment. However, when the standards are quite severe with
regard to the position of the image on the sheet, the sheets should
be strictly brought into alignment on the tray 12. Thus, when the
condition of the sheets 8 handled by the side walls is indicated,
the copying operation may be continued without interruption if the
operator is satisfied with the condition, and steps may be taken
for repeating the sheet aligning operation if he is dissatisfied
with the condition. If the indication is given by digital display
as set forth in paragraph (a), it is possible for the operator to
positively check the Magnitudes L.sub.1 and L.sub.2, making it easy
for him to make up his mind as to whether the sheet aligning
operation should be performed again.
In place of taking the steps described in paragraphs (a) and (b) or
simultaneously as they are taken, the actuating means for the side
walls 16 and 17 or the stepping motor in this embodiment may be
controlled to realign the sheets 8 as by increasing the frequency
of the reciprocatory movements of the side walls, when the
condition of the sheets 8 handled by the side walls 16 and 17 is
not satisfactory and the magnitudes L.sub.1 and L.sub.2 has
exceeded the predetermined levels. In this case, the sheet
realigning operation may be performed by increasing the frequency
of reciprocatory movements of the side walls 16 and 17, either by
interrupting or without interrupting the copying operation, during
the time the sheets 8 are successively conveyed to the tray 12.
Alternatively, the side walls 16 and 17 may be additionally moved
once or a few times to realign the sheets 8 after a predetermined
number of sheets 8 have been stacked on the tray 12. Also, the
effects of aligning the sheets 8 may be increased by decreasing the
speed or stroke of the reciprocatory movements of the side walls 16
and 17, so as to thereby realign the sheets 8 with a high degree of
efficiency.
The operation of realigning the sheets 8 either manually or by
means of the side walls 16 and 17 while the conveying of the sheets
8 to the tray 12 is interrupted may be advantageously performed
because a loss of time can be avoided. For example, realigning of
the sheets may be advantageously performed when steps are being
taken to eliminate a sheet jamming occurring in the path of travel
of the sheets in the copying apparatus, when a so-called cut-in
copying operation is performed in which one-side copying is
performed during the time both-sides copying is being performed or
by taking advantage of the time during which one document to be
copied is replaced by another document.
Other detection means than those shown in FIGS. 15-17 may be used
for checking the results achieved by the sheet aligning device 15.
For example, when the sheets 8 on the tray 12 are not properly
aligned, this may apply a load to the side walls 16 and 17 and make
it impossible for them to move to the phantom line positions shown
in FIG. 15. This fact may be taken advantage of and the results
achieved by the sheet aligning device 15 may be determined by
detecting the positions in which the side walls 16 and 17 have
become closest to each other or the distance between these
positions. FIG. 18 shows one example of such means. Assume that the
side wall 17 becomes closest to the side wall 16, not shown, when
the former moves to a one-dot between two-dashes position as the
sheets 8 are aligned in a predetermined position as indicated by
one-dot between two dashed lines. In this case, if the sheets 8 are
misaligned as indicated by two-dots between two-dashed lines, a
final position in which the side wall 17 becomes closest to the
side wall 16 is as indicated by two-dots between two-dashed lines.
The detecting means 87 shown in FIG. 18 comprises a light source 80
supported on the side wall 17 for movement as a unit therewith, and
a plurality of light receiving elements 81-86 located above the
tray 12 and arranged widthwise F of the sheets 8. As the side wall
17 moves into the final position designated by one-dot between
two-dashed lines, a light beam emanating from the light source 80
is incident on the light receiving element 85. If the final
position of the side wall 17 is as indicated by two-dots between
two-dashed lines, the light beam from the light source 80 is
incident on the light receiving element 83. Thus, by using the
incidence of the light beam from the light source 80 on the light
receiving element 85 when the side wall 17 reaches the final
position as a reference, it is possible to check the results
achieved by the sheet aligning device 15 by finding out on which
light receiving element the light beam from the light source 80 is
actually incident, to thereby learn how the sheets 8 have been
handled.
The stepping motor for driving the side walls 16 and 17 has
inputted thereto a predetermined number of pulses which may vary
depending on the width of the sheets 8 and rotates through an angle
determined by the inputted number of pulses. However, when the
sheets 8 are misaligned and the side wall 17 is unable to move to
the final position indicated by one-dot between two-dashed lines in
FIGS. 15-18, the angle through which the drive sprocket wheel 43
(FIG. 2) rotates will become smaller than the aforesaid angle
through which the steping motor rotates. By taking advantage of
this fact, detecting means 92 shown schematically in FIG. 19 is
provided which comprises a disc 88 secured to a rotary shaft 43a
supporting the drive sprocket wheel 43 (FIG. 2) for rotation, a
multiplicity of apertures 89 formed equidistantly in an outer
peripheral portion of the disc 88, and an optical sensor including
a light source 90 and a light receiving element 91 located in
spaced juxtaposed relation. The parts of the detecting means 92 are
positioned such that a light beam emanating from the light source
90 will pass through one of the apertures 89 before being incident
on the light receiving element 91. Thus, as the disc 88 rotates and
when each of the apertures 89 is interposed between the light
source 90 and light receiving element 91, the light beam from the
light source 90 is incident on the light receiving element 91.
Therefore, the number of times the light beam is incident on the
light receiving element 91 indicates the angle of rotation of the
disc 88 or the drive sprocket wheel 43. This indicates the distance
covered by the movement of the side wall 17.
Assume that the number of pulses inputted to the stepping motor for
driving the side walls 16 and 17 from their inoperative positions
indicated by solid lines to the predetermined final positions (when
no misalignment occurs) designated by one-dot between two-dashed
lines in FIG. 15 is n and that at this time the rotation of the
disc 88 brings the light beam from the light surce 90 into incident
on the light receiving element 91 through the apertures 89 which
are n.sub.1 in number. If the sheets 8 are misaligned and the final
position of the side wall 17 is one indicated by two-dots between
two-dashed lines in FIG. 18, for example, the angle of rotation of
the disc 88 will be reduced, and the number of apertures 89 through
which the light beam from the light source 90 passes will become
n.sub.2, for example. Thus, by comparing the numbers n.sub.2 and
n.sub.1 with each other, it is possible to determine the results
achieved by the sheet aligning device 15.
FIG. 20 shows another embodiment in which the side wall 17 is
supported by a support plate 117 through compression springs 93,
and the support plate 117 is slidably supported by guide rods and
driven by an endless chain in the same manner as described by
referring to the side wall 17 shown in FIG. 2. A switch 94 actuated
by the side wall 17 is mounted on the support plate 117 and
cooperates with the compression springs 93, side wall 17 and
support plate 117 to constitute detecting means 95. When the sheets
8 are stacked in the predetermined position in alignment with each
other, the side wall 17 and support plate 117 move to final
positions indicated by solid lines in FIG. 20. Assume that the
sheets 8 are misaligned and their lateral sides project toward one
side (downwardly in FIG. 20). Then, the support plate 117 is moved
to the final position indicated by the solid lines, but the side
wall 17 moves toward the side wall 17 a distance L.sub.3 as
indicated by two-dots between two-dashed lines, because the side
wall 17 is depressed by the sheets 8 and the compression springs 94
are compressed. This causes the switch 94 to be depressed by the
side wall 17 and turned on, thereby indicating that the sheets 8
are misaligned. In addition to the switch 94, a suitable number of
switches 96 and 97, for example, may be provided and operated in
such a manner that the second switch 96 is turned on as the side
wall 17 further moves close to the side plate 117 and the third
switch 97 is turned on as the side wall 17 moves closer to the side
plate 117. This enables the displacements of the sheets 8 widthwise
F thereof to be indicated step by step.
Detecting means similar to the detecting means shown and described
hereinabove by referring to the side wall 17 is provided to the
side wall 16 to detect the displacements of the sheets 8 upwardly
in FIG. 20. The detecting means 95a is similar in construction and
function to the detecting means 95, so that the parts of the
detecting means 95a will be designated by reference characters
designating the corresponding parts of the detecting means 95 but
having subscripts a added thereto and their detailed description
will be omitted.
The steps to be taken when the detecting means shown in FIGS. 18-20
is used to check the results achieved by the sheet aligning device
15 and the condition of the sheets 8 handled by the side walls 16
and 17 has been found, or indication of the condition of misaligned
sheets and realizing the sheets are performed in the same manner as
described by referring the detecting means shown in FIGS.
15-17.
The invention has been described as being incorporated in a sheet
aligning device comprising a pair of side walls 16 and 17 which are
moved toward and away from each other in reciprocatory movement to
bring sheets 8 into alignment with the center reference line G. It
is to be understood, however, that the invention is not limited to
the specific constructional form and that many changes and
modifications may be made therein. For example, one of the two side
walls may be firmly fixed and the other side wall may be moved in
reciprocatory movement to bring the sheets into alignment (one-side
reference). As shown in FIG. 21, a slanting roller 98 exerting on
the sheet 8 indicated by two-dots between two-dashed line in FIG.
21 which is conveyed to the tray in the direction E a force
oriented in a direction (indicated by an arrow E') skewed with
respect to the direction E may be provided to force the sheet 8
against the fixed side wall 217, so as to move the sheet 8 to a
one-dot between two-dashes position in which the sheet 8 is aligned
widthwise F thereof. This sheet aligning device may be provided
with detecting means 70 similar to the detecting means described by
referring to FIG. 17 which comprises the light sources 71-79 and
the light receiving elements 71a-79a associated therewith.
In a copying apparatus, a printer or peripheral equipment thereof
which is provided with a sheet aligning device, it is necessary to
monitor the sheets delivered to the sheet aligning device for the
purpose of checking whether or not the sheets successively conveyed
to the sheet aligning device are positively delivered or counting
the number of sheets delivered thereto.
A sheet aligning device capable of monitoring the sheets delivered
thereto will now be described.
FIG. 22 shows a portion of an intermediate sheet feeding device 301
located in the main body of a copying apparatus of a both-sides
copying type, not shown, comprising a tray 303 to which a sheet 302
having an image printed on one side surface thereof is delivered in
the direction of the arrow E. On the tray 303, the sheet 302 is
brought into alignment with a reference disposed perpendicular to
the direction E in which the sheet 302 is delivered by a sheet
aligning device 304.
The sheet aligning device 304 comprises a reference side wall 305
and a reciprocating side wall 306 extending in the direction E and
spaced apart from each other widthwise F of the sheet 302 to allow
the sheet 302 to be introduced into a space defined there between.
In the embodiment shown and described, as shown in FIGS. 22 and 23,
bases 305a and 306a of the side walls 305 and 306 respectively are
fitted in a cutout 307 (see FIGS. 24-28) formed in the tray 303 and
slidably supported on guide rods 308 secured to a lower portion of
the tray 303. The guide rods 308 extend widthwise F of the sheet
302 to allow the side walls 305 and 306 to move widthwise of the
sheet 302.
The reference side wall 305 is secured as indicated at 305b to an
endless chain 311 trained over a drive sprocket wheel 309 and a
follower sprocket wheel 310. Likewise, the reciprocating side wall
306 is secured as indicated at 306b to an endless chain 314 trained
over a drive sprocket wheel 312 and a follower sprocket wheel 313.
The drive sprocket wheels 309 and 312 are driven for rotation by an
actuating device, not shown, which comprise stepping motors for
driving the side walls 305 and 306 separately and independently of
each other. As the sprocket wheels 309 and 312 are driven for
rotation, the side walls 305 and 306 can move widthwise F of the
sheet 302 as described hereinabove.
The sheets 302 are fed from a main sheet feeding device, not shown,
and delivered to a printing station juxtaposed against a
photosensitive member, not shown, where they are printed and
conveyed to a fixing device, not shown, in which the images formed
on the sheets are fixed. From the fixing device, the sheets 302 are
delivered to the tray 303 of the intermediate sheet feeding device
301. When trouble occurs in the path of travel of the sheets 302,
they may not reach the tray 303. Thus, it is necessary to monitor
the sheets 302 during its travel from the main sheet feeding device
to the tray 303, and, if they fail to reach the tray 303, to detect
their failure to reach the tray 303 and inform the operator to let
him take necessary steps. The sheets 302 are delivered to the tray
303 in a predetermined number including one, and it is necessary to
sense their arrival at the tray 303 to count their number. Also, as
subsequently to be described, it is necessary to find out that the
sheet 302 has been placed on the tray 303 to control the time at
which the movement of the side walls 305 and 306 widthwise F of the
sheet 302 is initiated to bring the sheet 302 into alignment as
subsequently to be described.
To accomplish at least one of the aforesaid objects of detecting
the sheet 302, the sheet aligning device 304 is equipped with
detecting means comprising a reflection type photoelectric sensor
including a light source 315 and a light receiving element 316 as
shown in FIGS. 24-29. The sheet aligning device 304 operates as
follows to enable the detecting means to detect the leading edge of
a sheet.
When the sheet 302 designated by one-dot between two-dashed lines
in FIGS. 22-29 enters the space defined between the reference side
wall 105 and reciprocating side wall 306, the side walls 305 and
306 are disposed in standby or inoperative positions in which they
are spaced apart from each other a greater distance that the width
W of the sheet 302, so as not to interfere with the movement of the
sheet 302. In this case, the reference side wall 305 is disposed
outwardly, by a distance L.sub.4, of a reference position X for
finally positioning the sheet 302 widthwise of the reference
position X on the tray 303.
At a suitable time after the sheet 302 has started to enter the
space on the tray 303 between the side walls 305 and 306 after
having moved in the direction E, the drive sprocket wheel 312 is
driven for rotation by the stepping motor counterclockwise in FIG.
22 to move the reciprocating side wall 306 toward one lateral side
302b of the sheet 302, when a leading edge 302a of the sheet 302
impinges on a front striking bar 317 secured to the front
(rightside of tray in FIG. 24) of the tray 303 as shown in FIGS.
24-28 and stops. Thus, the reciprocating side wall 306 is moved and
forced against the sheet 302 until an opposite lateral side 302c of
the sheet 302 is brought into contact with the reference side wall
305 located in the standby position as shown in FIG. 26.
Then, the drive sprocket wheel 312 (FIG. 22) is rotated in the
reverse direction to move the reciprocating side wall 306 back, as
shown in FIG. 27, to the inoperative or standby position which is
also shown in FIG. 24, with a result that the side walls 305 and
306 are spaced apart a great distance from each other again, to
allow the next following sheet conveyed at an interval to the
preceding sheet 302 to enter the space between the side walls 305
and 306. The next following sheet is designated by two-dots between
two-dashed lines in FIG. 27 and designated by the reference numeral
402. When the next following sheet 402 enters the space between the
two side walls 305 and 306, it is displaced by a magnitude C
widthwise F of the preceding sheet 302.
Like the preceding sheet 302, the next following sheet 402 is
forced by the reciprocating side wall 306 against the reference
side wall 305 and stacked on the preceding sheet 302.
The aforesaid operation is repeatedly performed each time the sheet
is fed to the tray 33. When a predetermined number of sheets have
been stacked on the tray 303, the drive sprocket wheel 309 is
rotated counterclockwise in FIG. 22 to move the reference side wall
305 to the reference position X shown in FIG. 28, to bring the
sheets on the tray 303 into alignment with the reference position X
widthwise thereof. Thus, the sheets are positioned in a final
reference position. Then, the sheets on the tray 303 are fed one by
one by a sheet feeding roller, not shown, to the photosensitive
member again. Since the sheets have been aligned widthwise F
thereof with respect to the reference position X, it is possible to
positively move the sheets to a desired position in the printing
station juxtaposed against the developed image on the
photosensitive member. When the sheets on the tray 303 are fed
again therefrom to the photosensitive member, the reciprocating
side wall 306 is preferably brought into contact with the lateral
side 302b of the sheets or moved to a position close to the lateral
side 302b, to ensure that the sheets are positively guided.
The sheets are brought into alignment with the reference position X
as described hereinabove. Before the reciprocating side wall 306
begins to move force the sheet 402 newly delivered to the tray 303
against the reference side wall 305, the sheet 402 is displaced
widthwise F by a magnitude C from the sheets 302 already disposed
in the predetermined position or projects downwardly in FIG. 27. A
zone into which the sheet 402 projects will be referred to as a
projecting zone C. The light source 315 and light receiving element
316 referred to hereinabove are located in the projecting zone C to
detect the sheet which might project thereinto. More specifically,
a top surface of the tray 303 has a low light reflecting rate, so
that light emanating from the light source 315 is absorbed by the
top surface of the tray 303 when no sheet exists in the projecting
zone C and almost no light is incident on the light receiving
element 316. However, as shown in FIGS. 27 and 29, when the next
following sheet 402 enters the space between the side walls 305 and
306 and the sheet 402 projects into the projecting zone C, the
light emitted by the light source 315 is reflected by the sheet 402
and incident on the light receiving element 316. Thus, the entry of
the sheet 402 into the tray 303 is positively detected. The entry
of the preceding sheet 302 is, of course detected in like manner
(see FIG. 25).
The detecting means described hereinabove may be immovably secured
to the sheet aligning device. In the embodiment shown and described
hereinabove, however, the reflecting type photoelectric sensor
including the light source 316 and light receiving element 316 is
mounted on the reciprocating side wall 306 through a connector, not
shown, for movement as a unit with the side wall 306. This
arrangement offers the following advantages.
The size of the sheets used in a copying apparatus is usually
selected by the operator, so that a variety of sizes of sheets are
used. Thus, the sheets delivered to the intermediate sheet feeding
device vary in size depending on the desire of the operator.
Because of this, when the standby position of the reference side
wall 305 remains unchanged, the position of the reference side wall
305 remains unchanged, widthwise F of the sheets depending on the
size of the sheets delivered successively to the tray 303.
detecting means were immovably installed, it might be impossible to
detect the entry of the sheet in the projecting zone C in the event
of the size of the sheet was too small. To obviate this
disadvantage, the detecting means may comprise a plurality of
reflecting type photoelectric sensors arranged widthwise F of the
sheets, to enable to entry of the sheet of any size in the
projecting zone C to be detected, in spite of a change in the
position of the projecting zone C. However, this would cause a rise
in costs. In the embodiment shown and described hereinabove, the
detecting means is moveable together with the reciprocating side
wall 306 as a unit, so that it is possible to detect without fail
the entry of the sheet in the projecting zone C by the detecting
means in spite of a change in the position of the projecting zone C
merely by altering the standby position of the reciprocating side
wall 306 widthwise F of the sheets in accordance with the size of
the sheets handled to thereby alter the position of the detecting
means when the sheet enters the space between the two side walls on
the tray.
It would not be essential to secure the detecting means to the
reciprocating side wall 306, if it is possible to detect the entry
of a copy sheet in the projecting zone C without fail by altering
the position of the detecting means each time the position of the
projecting zone C changes. Alternatively, the standby position of
the reference side wall 305 may be altered widthwise F of the sheet
each time the size of the sheets handled changes, to keep the
position of the projecting zone C constant irrespective of the size
of the sheets to enable the immovably fixed detecting means, to
detect the entry of the sheet in the space between the side walls
305 and 306.
In the embodiment shown and described hereinabove, the entry of
sheets in the space between the side walls 305 and 306 is detected
when the sheets are conveyed in the direction E in which they are
conveyed. Alternatively, the sheet may be detected by a detecting
means which is movable with the reciprocating side wall 306 as a
unit when the latter is moved to force the sheet against the
reference side wall 305. This eliminates the need to alter the
standby position of the reciprocating side wall 306 depending on
the size of the sheets handled. However, it is not possible to use
the projecting zone C when the sheet is detected for the purpose of
controlling the timing with which the operation of the
reciprocating side wall 306 is commenced, because the sheet is
detected after the operation of the reciprocating side wall 306 has
begun.
As described hereinabove, the sheets are usually aligned widthwise
F by using two references. One reference is a center reference line
G (FIG. 2) and the other reference is a one-side reference. When
the sheets are aligned according to one-side reference in the
embodiment shown in FIGS. 24-28, it is not necessary to alter the
reference position X depending on the size of the sheets. However,
when the sheets are aligned in accordance with the center
reference, one only has to alter the reference position X widthwise
of the sheets depending on their size.
The construction of the embodiment shown in the drawings may
further be modified. For example, in place of using a reflecting
type photoelectric sensor 315, 316, a permeating type photoelectric
sensor including a tray formed with light permeating apertures, a
light source located on one side of the tray and a light receiving
element located on an opposite side of the tray. Alternatively,
detecting means having an actuator driven by a sheet may be
used.
* * * * *